If you've read Freakonomics, then you've probably read the section (pages 80 to 84) on online dating. I recently found a summary of the section that I though I'd share with you guys.
Freakonomics by Levitt and Dubner is a rather amazing book in which the
authors apply analytic techniques to all kinds of
questions that economists don't usually study. For
example, they show that Sumo wrestlers throw matches
to manipulate the standings. And that elementary
education teachers cheat for their students to raise
scores on standardized tests.
So, what does this have to do with Internet dating?
Well, Levitt and Dubner took data from a dating site
and answered the age-old question of what attracts
women to men and vice versa -- or at least what
features of an Internet dating ad attract the most
email in response.
Before reading on, try to guess what features in a
man's ad are most likely to attract women to respond.
Got your guess? OK, here is what they found:
1. Man is looking for a long term relationship.
2. Man is rich.
3. Man is tall.
So if you are Kareem Abdul Jabar looking to marry then
you're golden. But if you're short, poor, and looking
for casual sex then you may be lonely.
Now, what attracts a man to a woman. Got your guess?
OK, here is what Levitt and Dubner found:
1. Woman is looking for casual sex.
2. Woman is thin.
3. Woman is blond.
So, if you are Evilicious Blond looking for a
one-night stand then your going to see a lot of hits!
It's relatively easy to become blond. And it's
relatively easy to lie about your income and not get
caught (as long as you don't exaggerate too much). The
other variables are a bit harder to control...
Some other notes. For men weight was almost
irrelevant. For women, it was bad to be really poor or
really rich (presumably men find rich women
threatening).
For men, being balding was bad but
having a shaved head was good. 
Oh, and one last thing. You can't get away with not
including a picture. Levitt and Dubner write "A
low-income, poorly educated, unhappily employed,
not-very-attractive, slightly overweight, and balding
man who posts his photo stands a better chance of
gleaming some emails than a man who says he makes
$200,000 and is deadly handsome but doesn't post a photo."
